J. D. Everett on Reducing Observations of Temperature. 19 
three constants from the monthly means, is less than that of de- 
riving the monthly from the daily means. 
The constant A, as already stated, is the mean annual tem- 
perature. 
The constant E, represents the interval from that day in Au- 
tumn which forms the boundary between the warm and cold 
halves of the year to the 15th of January, the scale of represent- 
ation being such that 360° corresponds to an entire year. 
The constant A, (or the amplitude) is approximately equal to 
the difference between the mean temperature of the year and 
that of the warmest or coldest group of 30 days. More accu- 
rately it is proportional (but not equal) to the difference between 
the mean temperatures of the warm and cold halves of the year, 
bearing to this difference the constant value of 1:1-:2879. In 
speaking of the warm and cold halves of the year, I suppose the 
year divided at two opposite points, that is to say two points 
which are six months asunder, in such a manner that the great- 
est possible amount of heat shall be contained in one half, and 
(consequently) the greatest possible amount of cold in the other. 
In the definition here given of E, and in the second of the 
definitions of A,, not only annual harmonic variations, but also 
half-yearly, are taken into account. ‘ 
As a specimen of the manner in which the proposed method 
of reduction may be employed for comparing climates, I subjoin 
a table! showing its results as applied to all those stations of the 
Scottish Meteorological Society which have furnished observa- 
tions of temperature for the three years 1856-7-8. The data 
are the mean temperatures of the stations for each calendar 
Month, on the average of the 3 years above named, as given in 
the Society’s Report for the quarter ending June 80th, 1859. 
he names of stations are entered in the order in which they 
appear in the Society’s Reports, being nearly that of latitude, 
Proceeding from north to south. 
The first column of numbers contains the values of A, or the 
mean annual temperature, obtained in the usual manner. ; 
n thé second and third columns are the values of A, and E, 
Gaabltinde and epoch) determined in the manner already ex- 
ained, 
The fourth column shows the number of days and tenths of 
a day by which each station is earlier or later (as regards the 
Phases of the temperature) than the mean of all; days earlier 
than the mean being denoted by the sign +, and days later than 
the mean by the sign —. 
Fe The fifth column exhibits —_ peace ge ie the mean 
Mperatures of the warm and co ves of the year. 
The numbers in the fourth column have been obtained from 
! Table L. 
